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Pierreyves Gillot - One of the best experts on this subject based on the ideXlab platform.
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Geomorphic evolution of the piton des neiges volcano reunion island indian ocean competition between volcanic construction and erosion since 1 4 ma
Geomorphology, 2012Co-Authors: Tiffany Salvany, Pierre Lahitte, Pierre Nativel, Pierreyves GillotAbstract:Abstract Reunion Island (Indian Ocean) is a volcanic complex whose eruptive history was dominated by the activity of two main edifices: Piton des Neiges (PN) and Piton de la Fournaise (PF) volcanoes. The tropical climate induces erosion Processes that permanently compete with volcanic constructional Processes. Exposed to the trade winds and associated heavy rainfalls, the northeastern part of the island exhibits the most complex morphological evolution. Geomorphological analysis, performed on a 50 m DEM and associated to new K–Ar ages has clarified the overall history of PN volcano. Each massif is assigned to one of the main building stages of the edifice. In addition, the arrangement of these different massifs reveals that the eruptive phases have led to successive relief inversions and successive excavations of large central depressions in the proximal area. As a result, the younger massifs are always located in more proximal parts of the volcano, the youngest being close to the edifice center. In distal areas, early lava flows were channeled into valleys incised along the massif boundaries, leading to a more complex geochronological organization. Quantitative study of the dissection of PN volcano allows us to propose a minimum eroded volume of 101 ± 44 and 105 ± 41 km3 for the Mafate and Cilaos “Cirques” (depressions), respectively, during the last 180 kyr and a minimum average long-term erosion rate of 1.2 ± 0.4 km3/ka. This leads us to estimate the removed volume during the whole history of PN volcano (> 1000 km3) as equivalent to the volume of the deposits identified on the submarine flanks of Piton des Neiges volcano. Therefore, as regressive erosion appears to be the prevailing Geomorphic Process during the whole PN history, it questions the presence of major flank collapses younger than 1.4 Ma on this volcano. Erosion Processes have largely been neglected in recent models, but our study emphasizes them as a key component of landscape development and a major Process in the morphological evolution of Reunion Island that has to be fully integrated in future studies.
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Geomorphic evolution of the Piton des Neiges volcano (Reunion Island, Indian Ocean) : competition between volcanic construction and erosion since 1.4 Ma
Geomorphology, 2012Co-Authors: Tiffany Salvany, Pierre Lahitte, Pierre Nativel, Pierreyves GillotAbstract:Reunion Island (Indian Ocean) is a volcanic complex whose eruptive history was dominated by the activity of two main edifices: Piton des Neiges (PN) and Piton de la Fournaise (PF) volcanoes. The tropical climate induces erosion Processes that permanently compete with volcanic constructional Processes. Exposed to the trade winds and associated heavy rainfalls, the northeastern part of the island exhibits the most complex morphological evolution. Geomorphological analysis, performed on a 50 m DEM and associated to new K-Ar ages has clarified the overall history of PN volcano. Each massif is assigned to one of the main building stages of the edifice. In addition, the arrangement of these different massifs reveals that the eruptive phases have led to successive relief inversions and successive excavations of large central depressions in the proximal area. As a result, the younger massifs are always located in more proximal parts of the volcano, the youngest being close to the edifice center. In distal areas, early lava flows were channeled into valleys incised along the massif boundaries, leading to a more complex geochronological organization. Quantitative study of the dissection of PN volcano allows us to propose a minimum eroded volume of 101 +/- 44 and 105 +/- 41 km(3) for the Mafate and Cilaos "Cirques" (depressions), respectively, during the last 180 kyr and a minimum average long-term erosion rate of 1.2 +/- 0.4 km(3)/ka. This leads us to estimate the removed volume during the whole history of PN volcano (> 1000 km(3)) as equivalent to the volume of the deposits identified on the submarine flanks of Piton des Neiges volcano. Therefore, as regressive erosion appears to be the prevailing Geomorphic Process during the whole PN history, it questions the presence of major flank collapses younger than 1.4 Ma on this volcano. Erosion Processes have largely been neglected in recent models, but our study emphasizes them as a key component of landscape development and a major Process in the morphological evolution of Reunion Island that has to be fully integrated in future studies. (C) 2011 Elsevier B.V. All rights reserved.
Miska Luoto - One of the best experts on this subject based on the ideXlab platform.
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novel theoretical insights into Geomorphic Process environment relationships using simulated response curves
Earth Surface Processes and Landforms, 2011Co-Authors: Jan Hjort, Miska LuotoAbstract:Robust models of Geomorphic Process–environment relationships are important to advance theoretical knowledge of Geomorphic systems. Here, we examined a generalized additive modeling (GAM) based approach to provide new theoretical insights into Process–environment relationships. More precisely, we (i) simulated the shapes of the relationships between Geomorphic Processes and environmental variables based on GAM and (ii) compared the shapes of the simulated response curves to (a) the hypothetical curves based on theory and (b) the response curves produced by generalized linear modeling (GLM). Hitherto, GLM was the most common technique to study the relationships between environmental gradients and Geomorphic Processes. The study is based on empirical cryoturbation and solifluction data and environmental variables from subarctic Finland. Our results showed that non-linear relationships were more common than linear responses and the simulated GAM based response curves coincided more closely with the hypothetical response curves than did the response curves derived from GLM. The simulated response curves showed high potential in Geomorphic hypothesis testing. In conclusion, our findings indicate that careful examination of the response curves may provide new insights into theoretical debates in the earth sciences. Copyright © 2010 John Wiley and Sons, Ltd.
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Novel theoretical insights into Geomorphic Process–environment relationships using simulated response curves
Earth Surface Processes and Landforms, 2011Co-Authors: Jan Hjort, Miska LuotoAbstract:Robust models of Geomorphic Process–environment relationships are important to advance theoretical knowledge of Geomorphic systems. Here, we examined a generalized additive modeling (GAM) based approach to provide new theoretical insights into Process–environment relationships. More precisely, we (i) simulated the shapes of the relationships between Geomorphic Processes and environmental variables based on GAM and (ii) compared the shapes of the simulated response curves to (a) the hypothetical curves based on theory and (b) the response curves produced by generalized linear modeling (GLM). Hitherto, GLM was the most common technique to study the relationships between environmental gradients and Geomorphic Processes. The study is based on empirical cryoturbation and solifluction data and environmental variables from subarctic Finland. Our results showed that non-linear relationships were more common than linear responses and the simulated GAM based response curves coincided more closely with the hypothetical response curves than did the response curves derived from GLM. The simulated response curves showed high potential in Geomorphic hypothesis testing. In conclusion, our findings indicate that careful examination of the response curves may provide new insights into theoretical debates in the earth sciences. Copyright © 2010 John Wiley and Sons, Ltd.
Tiffany Salvany - One of the best experts on this subject based on the ideXlab platform.
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Geomorphic evolution of the piton des neiges volcano reunion island indian ocean competition between volcanic construction and erosion since 1 4 ma
Geomorphology, 2012Co-Authors: Tiffany Salvany, Pierre Lahitte, Pierre Nativel, Pierreyves GillotAbstract:Abstract Reunion Island (Indian Ocean) is a volcanic complex whose eruptive history was dominated by the activity of two main edifices: Piton des Neiges (PN) and Piton de la Fournaise (PF) volcanoes. The tropical climate induces erosion Processes that permanently compete with volcanic constructional Processes. Exposed to the trade winds and associated heavy rainfalls, the northeastern part of the island exhibits the most complex morphological evolution. Geomorphological analysis, performed on a 50 m DEM and associated to new K–Ar ages has clarified the overall history of PN volcano. Each massif is assigned to one of the main building stages of the edifice. In addition, the arrangement of these different massifs reveals that the eruptive phases have led to successive relief inversions and successive excavations of large central depressions in the proximal area. As a result, the younger massifs are always located in more proximal parts of the volcano, the youngest being close to the edifice center. In distal areas, early lava flows were channeled into valleys incised along the massif boundaries, leading to a more complex geochronological organization. Quantitative study of the dissection of PN volcano allows us to propose a minimum eroded volume of 101 ± 44 and 105 ± 41 km3 for the Mafate and Cilaos “Cirques” (depressions), respectively, during the last 180 kyr and a minimum average long-term erosion rate of 1.2 ± 0.4 km3/ka. This leads us to estimate the removed volume during the whole history of PN volcano (> 1000 km3) as equivalent to the volume of the deposits identified on the submarine flanks of Piton des Neiges volcano. Therefore, as regressive erosion appears to be the prevailing Geomorphic Process during the whole PN history, it questions the presence of major flank collapses younger than 1.4 Ma on this volcano. Erosion Processes have largely been neglected in recent models, but our study emphasizes them as a key component of landscape development and a major Process in the morphological evolution of Reunion Island that has to be fully integrated in future studies.
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Geomorphic evolution of the Piton des Neiges volcano (Reunion Island, Indian Ocean) : competition between volcanic construction and erosion since 1.4 Ma
Geomorphology, 2012Co-Authors: Tiffany Salvany, Pierre Lahitte, Pierre Nativel, Pierreyves GillotAbstract:Reunion Island (Indian Ocean) is a volcanic complex whose eruptive history was dominated by the activity of two main edifices: Piton des Neiges (PN) and Piton de la Fournaise (PF) volcanoes. The tropical climate induces erosion Processes that permanently compete with volcanic constructional Processes. Exposed to the trade winds and associated heavy rainfalls, the northeastern part of the island exhibits the most complex morphological evolution. Geomorphological analysis, performed on a 50 m DEM and associated to new K-Ar ages has clarified the overall history of PN volcano. Each massif is assigned to one of the main building stages of the edifice. In addition, the arrangement of these different massifs reveals that the eruptive phases have led to successive relief inversions and successive excavations of large central depressions in the proximal area. As a result, the younger massifs are always located in more proximal parts of the volcano, the youngest being close to the edifice center. In distal areas, early lava flows were channeled into valleys incised along the massif boundaries, leading to a more complex geochronological organization. Quantitative study of the dissection of PN volcano allows us to propose a minimum eroded volume of 101 +/- 44 and 105 +/- 41 km(3) for the Mafate and Cilaos "Cirques" (depressions), respectively, during the last 180 kyr and a minimum average long-term erosion rate of 1.2 +/- 0.4 km(3)/ka. This leads us to estimate the removed volume during the whole history of PN volcano (> 1000 km(3)) as equivalent to the volume of the deposits identified on the submarine flanks of Piton des Neiges volcano. Therefore, as regressive erosion appears to be the prevailing Geomorphic Process during the whole PN history, it questions the presence of major flank collapses younger than 1.4 Ma on this volcano. Erosion Processes have largely been neglected in recent models, but our study emphasizes them as a key component of landscape development and a major Process in the morphological evolution of Reunion Island that has to be fully integrated in future studies. (C) 2011 Elsevier B.V. All rights reserved.
Jean Poesen - One of the best experts on this subject based on the ideXlab platform.
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soil loss due to crop harvesting in the european union a first estimation of an underrated Geomorphic Process
Science of The Total Environment, 2019Co-Authors: Panos Panagos, Pasquale Borrelli, Jean PoesenAbstract:Over the last two decades or so, there has been many research carried out to understand the mechanics and spatial distribution of soil loss by water erosion and to a lesser extent of wind, piping and tillage erosion. The acquired knowledge helped the development of prediction tools useful to support decision-makers in both ex-ante and ex-post policy evaluation. In Europe, recent studies have modelled water, wind and tillage erosion at continental scale and shed new light on their geography. However, to acquire a comprehensive picture of soil erosion threats more Processes need to be addressed and made visible to decision-makers. Since 1986, a small number of studies have pointed to an additional significant soil degradation Process occurring when harvesting root and tuber crops. Field observations and measurements have shown that considerable amounts of soil can be removed from the field due to soil sticking to the harvested roots and the export of soil clods during the crop harvest. This study aims to scale up the findings of past studies, carried out at plot, regional, and national level, in order to obtain some preliminary insights into the magnitude of soil loss from cropland due to sugar beets and potatoes harvesting in Europe. We address this issue at European Union (EU) scale taking into account long-term (1975-2016) crop statistics of sugar beet and potato aggregated at regional and country levels. During the period 2000-2016, sugar beets and potatoes covered in average ca. 4.2 million ha (3.81%) of the EU-28 arable land estimated at 110 million ha. The total Soil Loss by Crop Harvesting (SLCH) is estimated at ca. 14.7 million tons yr-1 in the EU-28. We estimate that ca. 65% of the total SLCH is due to harvesting of sugar beets and the rest as a result of potatoes harvesting.
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Reconstructing environmental changes since the Last Glacial Maximum(LGM) in the Geba basin, Northern Ethiopia, by Geomorphic Process interpretation and land management evaluation
2010Co-Authors: Jan Moeyersons, Jozef Deckers, Jean Poesen, Jan Nyssen, Mitiku HaileAbstract:The palaeoenvironmental evolution of the Geba Basin in Northern Ethiopia since the Last Glacial Maximum (LGM) certainly is a good indicator for the climatic conditions, but there is evidence that climate has been affected by the interference of humans with the hydrological cycle, especially since the second half of the Holocene. Before -15 cal ley BP, Ethiopia knew a dry climate in the lower parts and cold and also dry conditions in the Simen and Bale Mountains, in phase with the LGM. But while elsewhere in Ethiopia the cold/dry conditions continued till -10-11 cal ley BP, the Geba Basin enjoyed moist conditions from -15 cal ley BP onwards and no clear explanation can be given for this. These conditions continued in Tsigaba till -3 cal ky BP and in many valley bottoms, till 50 years ago or even nowadays. This article presents evidence suggesting that the 'arid environmental conditions' which started in some places as early as -5 cal ky BP, in other places only very recently, are more a human-induced than an astronomically steered phenomenon. Our research indicates that man has the necessary tools to bend off the present tendency towards aridification.
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soil losses due to harvesting of chicory roots and sugar beet an underrated Geomorphic Process
Catena, 2001Co-Authors: Jean Poesen, Gert Verstraeten, Ruben Soenens, Leen SeynaeveAbstract:Abstract Field observations in central Belgium indicate a significant soil degradation Process which has hitherto not been considered in assessments of soil erosion rates: i.e., soil losses due to root crop harvesting (SLRH). The objectives of this study were: (1) to assess SLRH for two commonly grown root crops in Belgium, i.e. chicory roots and sugar beet, (2) to investigate some factors controlling the spatial and temporal variation of SLRH, and (3) to evaluate the contribution of this soil degradation Process to overall soil loss in the study area. Soil losses due to harvesting of witloof chicory roots were assessed by measuring dirt tare from 43 root samples whereas SLRH for inuline chicory roots and sugar beet were calculated from dirt tare data provided by factories Processing these roots. Mean soil loss was 11.8 ton ha −1 harvest −1 for witloof chicory roots, 8.1 ton ha −1 harvest −1 for inuline chicory roots and 9.1 ton ha −1 harvest −1 for sugar beet. Assuming that root crops are grown once in 2 years in the study area, mean annual SLRH equals 5.0 ton ha −1 year −1 (0.33 mm/year). Since these root crops have been grown over a period of at least 200 years in Belgium, this implies a mean soil profile truncation of 66 mm. However, important spatial and temporal variability in SLRH data was observed, depending on soil texture, soil moisture at harvest time and harvesting technique. Given the importance of SLRH, it needs to be incorporated into future assessments of soil degradation Processes and sediment budgets.
Jan Hjort - One of the best experts on this subject based on the ideXlab platform.
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novel theoretical insights into Geomorphic Process environment relationships using simulated response curves
Earth Surface Processes and Landforms, 2011Co-Authors: Jan Hjort, Miska LuotoAbstract:Robust models of Geomorphic Process–environment relationships are important to advance theoretical knowledge of Geomorphic systems. Here, we examined a generalized additive modeling (GAM) based approach to provide new theoretical insights into Process–environment relationships. More precisely, we (i) simulated the shapes of the relationships between Geomorphic Processes and environmental variables based on GAM and (ii) compared the shapes of the simulated response curves to (a) the hypothetical curves based on theory and (b) the response curves produced by generalized linear modeling (GLM). Hitherto, GLM was the most common technique to study the relationships between environmental gradients and Geomorphic Processes. The study is based on empirical cryoturbation and solifluction data and environmental variables from subarctic Finland. Our results showed that non-linear relationships were more common than linear responses and the simulated GAM based response curves coincided more closely with the hypothetical response curves than did the response curves derived from GLM. The simulated response curves showed high potential in Geomorphic hypothesis testing. In conclusion, our findings indicate that careful examination of the response curves may provide new insights into theoretical debates in the earth sciences. Copyright © 2010 John Wiley and Sons, Ltd.
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Novel theoretical insights into Geomorphic Process–environment relationships using simulated response curves
Earth Surface Processes and Landforms, 2011Co-Authors: Jan Hjort, Miska LuotoAbstract:Robust models of Geomorphic Process–environment relationships are important to advance theoretical knowledge of Geomorphic systems. Here, we examined a generalized additive modeling (GAM) based approach to provide new theoretical insights into Process–environment relationships. More precisely, we (i) simulated the shapes of the relationships between Geomorphic Processes and environmental variables based on GAM and (ii) compared the shapes of the simulated response curves to (a) the hypothetical curves based on theory and (b) the response curves produced by generalized linear modeling (GLM). Hitherto, GLM was the most common technique to study the relationships between environmental gradients and Geomorphic Processes. The study is based on empirical cryoturbation and solifluction data and environmental variables from subarctic Finland. Our results showed that non-linear relationships were more common than linear responses and the simulated GAM based response curves coincided more closely with the hypothetical response curves than did the response curves derived from GLM. The simulated response curves showed high potential in Geomorphic hypothesis testing. In conclusion, our findings indicate that careful examination of the response curves may provide new insights into theoretical debates in the earth sciences. Copyright © 2010 John Wiley and Sons, Ltd.